title: Crystal-plane-controlled surface chemistry and catalytic performance of surfactant-free Cu2 O nanocrystals.
abstract: Surfactant-free Cu2 O nanocrystals, including cubes exposing {100} crystal planes, octahedra exposing {111} crystal planes, and rhombic dodecahedra exposing {110} crystal planes, were used as model catalysts to study the effect of the crystal plane on the surface chemistry and catalytic performance for CO oxidation of Cu2 O nanocrystals. The catalytic performance follows the order of octahedra rhombic dodecahedra>cubes; this suggests that Cu2 O(111) is most active in catalyzing CO oxidation among Cu2 O (111), (110), and (100) surfaces. CO temperature-programmed reduction results demonstrate that Cu2 O octahedra are the most easily reduced of the Cu2 O cubes, octahedra, and rhombic dodecahedra. Diffuse reflectance FTIR spectra show that CO chemisorption on Cu2 O nanocrystals depends on their shape and the chemisorption temperature. CO chemisorption is strongest on rhombic dodecahedra at 30°C, but at 150°C on octahedra. Both the reducibility and chemisorption ability of various Cu2 O nanocrystals toward CO are consistent with their catalytic performance in CO oxidation. The observed surface chemistry and catalytic performance in CO oxidation of various Cu2 O nanocrystals can be well correlated with their exposed crystal plane and surface composition/structure. Cu2 O octahedra expose the {111} crystal plane with coordinated, unsaturated Cu(I) sites, and thus, are most active in chemisorbing CO and catalyzing CO oxidation. These results nicely demonstrate the crystal-plane-controlled surface chemistry and catalytic performance of oxide catalysts.
authors.affiliation: Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Materials for Energy Conversion, Department of Chemical Physics, University of Science and Technology of China, Jinzhai Road 96, Hefei 230026 (P.R. China).
authors.forename: Qing
authors.initials: Q
authors.lastname: Hua
authors.forename: Tian
authors.initials: T
authors.lastname: Cao
authors.forename: Huizhi
authors.initials: H
authors.lastname: Bao
authors.forename: Zhiquan
authors.initials: Z
authors.lastname: Jiang
authors.forename: Weixin
authors.initials: W
authors.lastname: Huang
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D013501:Surface-Active Agents; D003300:Copper; D002248:Carbon Monoxide; D010100:Oxygen; C000520:cuprous oxide
keywords: chemisorption; heterogeneous catalysis; nanostructures; oxidation; surface chemistry